JPH02201467A - Image forming method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming method for scanning a light beam to create an image on a recording medium according to an image forming signal.

[Prior Art] FIG. 5 is a diagram showing a potential distribution due to scanning with a fixed amount of laser light in a conventional image forming method. Figure 5 (
a) shows an example of pixel information of an image to be recorded, and pixel 3
It consists of 5-1 to 35-10. 35-2.35-4
．． 35-5.35-7.35-8.35-9 are the pixels to be recorded, and 35-1.35-3.35-6.35-1
0 is a pixel that is not recorded. In response to such pixel information, the laser was turned on and off as shown in FIG. 5(b). Therefore, when a laser having a predetermined amount of light is controlled on and off in this manner and a light beam is irradiated onto a recording medium having photosensitivity, a potential distribution as shown in 5m(c) is obtained on the recording medium. However, the horizontal axis is the distance taken in the scanning direction from the reference point on the photoreceptor.

In this FIG. 5(C), when comparing the potential distribution of each pixel, it is found that the independently recorded pixel 35-2, in which the adjacent pixels before and after in the scanning direction are not recorded, is the case where both the adjacent pixels before and after are recorded continuously. The potential is lower than that of pixel 35-8. Further, even when one of the adjacent pixels before and after the pixel 35-4 and 35-5 is recorded and the other is not recorded, the potential is lower than that of the above-mentioned pixel 35-8.

[Problems to be Solved by the Invention] However, the above-mentioned conventional technology has a problem in that the potential of the recording dot changes depending on whether or not surrounding pixels are recorded, making the image unclear.

SUMMARY OF THE INVENTION The present invention aims to solve the above-mentioned problems, and its purpose is to provide means for modulating the light intensity of a scanning light beam so that each recording dot can independently obtain a predetermined potential. An object of the present invention is to provide an image forming method in which the density of the image can be arbitrarily controlled.

[Means for Solving the Problems] The image forming method of the present invention modulates a light beam in response to an image forming signal and scans the light beam on the recording medium, thereby creating an electrostatic latent image on the recording medium. In an image forming method for forming an image, a control signal is generated to control the amount of light at a pixel to be recorded according to the recording state of a pixel adjacent to the pixel to be recorded on a recording medium, and the intensity of the light beam is controlled by the control signal. It is characterized by electro-optical modulation.

[Operation] According to the above configuration of the present invention, each pixel is processed by processing a signal indicating the recording state of pixels surrounding the recording pixel in a logic circuit, and modulating the light beam intensity electro-optically according to the result. The potential of each can be controlled independently, and an image with stable density can be formed.

The electro-optic modulation element of the present invention is an element having an electro-optic effect represented by the Franz-Kjelditzsch effect,
For example, it has a shape in which a Ga/GaAs multi-well structure is sandwiched between transparent electrodes. In a multi-quantum well structure, electrons and holes are confined in a narrow space, so excitons stably exist even at room temperature and in a high electric field.

FIG. 4 is a diagram showing the light absorption characteristics of an electro-optical element using the Franz-Kjelditssch effect used in the embodiment of the present invention. GaA s / Ga when no electric field is applied
When an electric field is applied to an electro-optical element whose light absorption of the AIAs layer is 36 in the figure, the absorption edge shifts to the lower energy side, resulting in light absorption as 37 in the figure.

If the light from the semiconductor laser that is the light source has the energy distribution shown in 38 in the figure, the light beam can be absorbed by applying an electric field, and the intensity of the light beam can therefore be modulated. In addition, the Franz Kjelditssch effect is caused by many GaA
It has been confirmed in semiconductor crystals represented by S.

[Example] Hereinafter, the present invention will be explained in detail based on examples.

FIG. 1 is a schematic diagram of an image forming method including a modulation signal generation circuit and an electro-optic modulator in an embodiment of the present invention. In FIG. It is. The applied image forming signals are sequentially stored in the frame memory 2. The signals temporarily stored in the frame memory 2 are sequentially input to the block forming circuit 3.

The block forming circuit 3 uses a shift register composed of line buffers 4 and 5 and D flip-flops (DFF) 6 to 11 to generate 3×3 pixel signals D1 to D9 with timing controlled by a timing controller 12. Take it out.

13 in the figure is a signal processing circuit. The signal of the pixel of interest is D5, and the signals of surrounding pixels D1 to D4 . D
6 to D9 are added by the adder 14 and subtracted from the reference value by the subtracter 15. The value of subtractor 15 is added to multiplier 1 along with D5.
6 and is multiplied. The output of this multiplier 16 is boosted by an amplifier 17 to the bias level of the electro-optical element, and is connected to the electro-optical element 18.

The output voltage of the amplifier 17 is applied as a bias between the transparent electrodes 19 and 20. Transparent electrode 19.20
An electro-optical element 21 having a Ga/GaAs multi-quantum well structure is sandwiched between them. The light beam from the light source illuminates the transparent electrode 20, and the transparent electrodes 19 and 20
By changing the absorption rate of the electro-optical element depending on the voltage (electric field) applied between the transparent electrode 19 and the transparent electrode 19, intensity-modulated transmitted light can be obtained.

Incidentally, in the above embodiment, an example was shown in which one block is constituted by a matrix of 3.times.3 pixels, but a block forming circuit in which one block is a matrix of any size can also be used. Further, in the signal processing circuit 13, D1 to D9 are inputted as they are to the adder, but it is also possible to weight the peripheral pixels by multiplying them by coefficients using a coefficient multiplier and then adding them. and amplifier 17
Processing using a nonlinear amplifier such as a log amplifier is also considered. Furthermore, by combining the above processes, it is also possible to control the potential of the portion corresponding to the edge of the image, thereby promoting or suppressing the edge effect in electrophotographic development.

FIG. 3 is a diagram showing a signal change from an image signal to a modulation signal. FIG. 3(a) is a diagram showing the recording state of pixels for three lines, 34-1.34-3°34-5.34-6
．． 34-7.34-9.34-10.34-11 are pixels to be recorded, and 34-2.34-4.34-8 are pixels not to be recorded. FIG. 3(b) shows pixels 34-1 to 34-3.
The result of subtraction from the level shown at 34 in Figure 0, which is the signal corresponding to DIO in Figure 1, corresponding to 4-11, is shown in Figure 3(c). The signal corresponding to D5 in the figure is shown in FIG. 3(d),
The result of multiplying (c) and (d) (D12 in FIG. 1) is shown in FIG. 3(e). Based on the signal shown in (e),
As a result of modulating the light beam intensity by applying a voltage to the electro-optical element, a surface potential shown in FIG. 3(f) is obtained on the recording medium.

FIG. 2 is a schematic diagram of an image forming method using a semiconductor laser as a light source in another embodiment of the present invention.

In the figure, 23 indicates a pixel signal for recording, a semiconductor laser 25 that processes the pixel signal 23, and an electro-optic modulator 26.
24 is a signal processing circuit that drives the . Electro-optic modulator 26 consisting of an electro-optic element and optical components such as lenses
modulates the intensity of the light beam from the semiconductor laser 25 based on the signal from the signal processing circuit 24. A lens 27 condenses the emitted light from the electro-optic modulator 26 and irradiates the rotating polygon mirror 28 . The light beam 33 is horizontally swept by a rotating polygon mirror 28 driven by a motor 29, and
- An image is formed as a spot on the photoreceptor drum 31 by the optical system 30 including an imaging lens having θ characteristics. The photoreceptor 31 is made of Se, a-8i, or Zn with photosensitivity.
It consists of substances such as O and OPC.

The beam detector 32 detects the position of the swept light beam 33, and the processing circuit 24 determines the line start timing based on this detection signal. Further, the photosensitive drum 31 is charged to several hundred volts using, for example, a scorotron.
The point irradiated with the light beam loses its charge and forms an electrostatic latent image in response to the irradiated light. Thereafter, charged colored particles called toner are attached depending on the contrast of the electrostatic latent image, and the electrostatic latent image is visualized by regular development or reverse development.

In the embodiment shown in FIG. 2, a semiconductor laser is used as the light source, but a gas laser, LED, etc. may also be used.
Further, a sheet-like photoreceptor may be used instead of the photoreceptor drum.

Although the embodiments have been described above, the present invention is particularly effective when applied not only to the above embodiments but also to a wide range of image forming apparatuses such as displays and electrophotographic recording apparatuses, such as page printers, facsimiles, and copying machines.

[Effects of the Invention] As described above, according to the present invention, it is possible to stably control the potential of each dot by providing the recording medium with an amount of light that corresponds to the recording state of pixels surrounding the pixel to be recorded. can. By controlling the image density of each dot to be uniform, expression by area gradation becomes possible, and since the image density of each dot can be controlled, temperature gradation expression is also possible.

That is, it has the effect of providing a high-quality image forming method capable of expressing gradations.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a signal change to an approximate signal in an image forming method including a modulation signal generation circuit and an electro-optic modulator in an embodiment of the present invention, and FIG. - It is a diagram showing the potential distribution by scanning with a fixed Keldeitssch effect amount. 18... Electro-optical element 24... Image signal processor 25... Semiconductor laser 26... Electro-optic modulator 31... Photoconductor drum or more Applicant: Seiko Epson Corporation

Claims (1)

[Claims] An image forming method in which an electrostatic latent image is formed on the recording medium by modulating a light beam in response to an image forming signal and scanning the light beam over the recording medium, the method comprising: A control signal for controlling the amount of light of the pixel to be recorded is generated according to a recording state of a pixel adjacent to the pixel to be recorded, and the intensity of the light beam is electro-optically modulated by the control signal. Image forming method.